Solve and find the value of x

5^(x-7) = 8

The standard distance between studs in a house is 1.5 feet. if you have a set of blueprints for a house that mark every 1.5 feet with 2 in., by how many inches will a 13-foot wall be represented?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Aquadratic equation in standard from is written ax^2= bx+c, where a, b and c are real numbers and a is not zero?